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What determines which current sensor / set I need?

It is best to use a current sensor that is close to the current that is most common in your set-up. Suppose the nominal current is 80A, with pieks of 150A, then you are best off with a current sensor of 100A. This will be more accurate in this working area than a current sensor of 250A.

Which type of batteries can I use this BMS?

The BMS cell boards work in a voltage range from 2V to 5V. Every cell that operates between this voltage should be compatible. A couple of working cell chemistry examples are LiFePO4, NMC and NCA.

Can I use only one current sensor instead of two?

It is possible to only use 1 current sensor, the BMS will also work perfectly fine. Using one sensor will use less power on the IN board. The drawback is that you cannot measure incoming and outgoing currents independently, but only see the current going in or out the battery pack. Connect the current sensor to J1 on the IN board and make sure to see a positive current in the App next to the battery icon when charging and a negative current when discharging.

Can I place multiple cells or packs parallel?

There is a difference between placing multiple cells parallel or packs parallel.

Multiple cells parallel

You can safely place multiple cells parallel and only need 1 BMS cell module per parallel group. For instance: a 12V LiFePO4 pack consists of 4 cell groups in series. In case you have 8 cells, the pack is configured as 2P4S (groups of 2 cells parallel, then these parallel groups in series). In this case you only need 1 BMS for 4S (4 cell groups).

Multiple battery packs parallel

When you have to connect multiple packs parallel, you need 1 complete BMS per pack. You can connect the signal relays on each OUT board in series. For instance: with 3 packs parallel, you can run the charging signal through from the first OUT boa rd Charge relay to the second Charge relay and through the third Charge relay. This signal can switch an enable/disable or power relay. The same goes for the Load relays in series.

My BMS has no communication.

No battery data on the app and the “E” sign will light ON in the battery details tab of the App. Check the flashing LEDs on the string of cells. The position where the LED’s stop flashing is the location of the problem. Check if the wiring is connected in the right position of the communication connectors.

Indicated currents are not zero while no current is being drawn.

Make sure there is running absolutely no current through the current sensors during the zero calibration procedure. On the IN module you will find the option switches. Set option switch number 4 to the ON position. Now the “set to zero” procedure will be active. The currents on the App screen will show 0 ampere in a couple of seconds. Set the option switch number 4 back to the OFF position again. Also set option switch number 3 to ON as the blind spot is recommended.